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Defined in header <stdatomic.h> | ||
C atomic_fetch_or(volatile A* obj, M arg); | (1) | (since C11) |
C atomic_fetch_or_explicit(volatile A* obj, M arg,memory_order order); | (2) | (since C11) |
Atomically replaces the value pointed byobj with the result of bitwise OR between the old value ofobj andarg, and returns the valueobj held previously. The operation is read-modify-write operation. The first version orders memory accesses according tomemory_order_seq_cst, the second version orders memory accesses according toorder.
This is ageneric function defined for allatomic object typesA. The argument is pointer to a volatile atomic type to accept addresses of both non-volatile andvolatile (e.g. memory-mapped I/O) atomic objects, and volatile semantic is preserved when applying this operation to volatile atomic objects.M is either the non-atomic type corresponding toA ifA is atomic integer type, orptrdiff_t ifA is atomic pointer type.
It is unspecified whether the name of a generic function is a macro or an identifier declared with external linkage. If a macro definition is suppressed in order to access an actual function (e.g. parenthesized like(atomic_fetch_or)(...)), or a program defines an external identifier with the name of a generic function, the behavior is undefined.
Contents |
| obj | - | pointer to the atomic object to modify |
| arg | - | the value to bitwise OR to the value stored in the atomic object |
| order | - | the memory synchronization ordering for this operation: all values are permitted |
The value held previously be the atomic object pointed to byobj.
| atomic bitwise AND (function)[edit] | |
| atomic bitwise exclusive OR (function)[edit] | |
C++ documentation foratomic_fetch_or,atomic_fetch_or_explicit | |
